How Coffee Makers Work

A modern drip coffee maker is a surprisingly simple device. Manufacturers have had more than 30 years to hone their designs, so these coffee makers are pretty straightforward once you open them up.

If you take off the top of the coffee maker, you find three things:

There's a reservoir that holds the water when you pour it into the pot at the start of the coffee-making cycle (on the right in the picture above). At the bottom of the bucket there's a hole, and its role will become obvious in a moment.

There's a ­white tube that leads up from below the reservoir base, carrying the hot water up to the drip area.

There is a shower head (on the left-hand side of the picture). Water arrives here from the white hot-water tube and is sprayed over the coffee grounds. In some coffee makers, the water comes out of the hose onto a perforated plastic disc called the drip area and simply falls through the holes into the coffee grounds.

Looking at this picture, you get your first impression that this isn't a high-tech device. If you take the bottom off the coffee maker, here's what you'll find:

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Things are about to start heating up!

HowStuffWorks 2008

The depression on the right-hand side of this figure is the bottom of the bucket. The orange tube on the top picks up the cold water coming down from the hole in the reservoir. The orange tube on the bottom is the hot-water tube (it connects to the white tube that we saw in the previous picture). You can also see the power cord coming in as well.

On the left-hand side of the base of the coffee maker is the heating element. This component is comprised of an aluminum extrusion with two parts: a resistive heating element and a tube for water to flow through. The resistive heating element and the aluminum tube heat the water. On the next page, we'll take a closer gander at what this apparatus looks like.